Methylene-dithiolans

ABSTRACT

The present invention relates to the preparation of methylenedithiolans able to carry various substitutions on their carbons and more especially on the carbon connected by the double methylenic bond to that of position 2. Dithiolans are heterocyclic compounds containing 2 atoms of sulphur in a cycle having 5 elements. These substances are useful as sulphurants, for example, for the progressive and controlled sulphuration of metals or other materials. Methylene-dithiolans can, moreover, give rise to various interesting reactions, thanks to their double bond between the carbon in position 2 and a carbon exterior to the cycle.

United States Patent [19 1 Donche et al.

[ 1 'Apr.3, 1973 [54] METHYLENE-DITHIOLANS [75] Inventors: Alain Douche,Lescar; Claude Thihault, Pau; Emmanuel Arretz, Pau; Alain Pfister, Pau,all of France [73] Assignee: Societe ,Nationale' des PetrolesDAquitaine,-Courbevoie, France [22] Filed: June 23, 1969 [21] Appl. No.:835,772

[30] Foreign Application Priority Data Chemical Abstracts, Vol. 60, C01.15853 (1964) (abstract of Jentzsch et al.). Mayer et al., Angew. Chem.Internat. Edit. Vol. 1,

pages 217 to 218 (I962). Wizinger et al. I. Chimia Vol. 12, pages 79-81(1956).

Soder et al., l-lelv. Chim. Acta Vol. 42, pages l,779-l,7 82 and1,7844785 (1959).

Kirmse et al., Annalen der Chemie, Vol. 6l4,'pages l A Condo etaL, J.Am. Chem. Soc. Vol. 59, pages-230 to I 1 I-Iauben-Weyl, Methoden derOrganischen Chemie, 4th Ed., Band 1X, pp. 762 to 763, Georg ThiemeVerlag, Stuttgart, Germany (1955).

Primary Examiner-John D. Randolph Attorney- Norman S. Blodgett [57]ABSTRACT The present invention relates to the preparation ofmethylene-dithiolans able to carry varioussubstitutions on their carbonsand more especially on the carbon connected by the double methylenicbond to that of position 2. Y

Dithiolans are heterocyclic compounds containing, 2 atoms of sulphur ina cycle having 5 elements. These substances are useful as sulphurants,for example, for the progressive and controlled sulphuration'of metalsor other materials. Methylene-dithiolans moreover, give rise to variousinteresting reactions, thanks to their double bond between the carbon inposition 2 and a carbon exterior to the cycle.

9 Claims, No Drawings .can,

METHYLENE-DITHIOLANS The present invention permits methylene-dithiolansto be obtained conveniently and economically from easily accessibleprimary materials.

The new process consists in making a a-dithiol react with a nitrilepossessing at a a methylenic group.

Preferably, the reaction is catalysed byan organic basic substance,notably an amine, especially aliphatic tertiary amines, preferably C toC the use of amines such as triethylamine, tripropylamine,tributylamines or trihexylamines is very practical. I

Although the temperature of the operation can vary according to thenature of the particular dithiols and nitriles that are to be condensed,it is generally comprised between 100 and 250 C. The temperaturesmost'used, with aliphatic dithiols, are of the order of 130 to 180 C,and more especially 140 to 160 C; they are preferably from 170 to 220 Cfor the aromatic dithiols.

The a-dithiol, used in accordance with the invention, carries its twogroups -SH on two neighboring carbons of a chain or of ahydrocarbonaceous cycle, possibly substituted. When the dithiolcomprises an aliphatic chain, the number of carbon atoms in this chaincan very widely, for example, from two up to 30, but it is most oftenfrom two to 12. Thus, for example, the invention can be realized fromdithiols such as ethanedithiol-1.2, propane-dithiol-1.2,butane-dithiol-2.3 butane-dithiol-1.2, pentane-dithiol-2.3,octane-dithiol- 3.4, phenyl-l-propane-dithiol-1.2,cyclo-hexyl-l-butane-dithiol-2.3, etc. In the case of the cyclicalphadithiols, their cycle or cycles aromatic or cycloaliphatic can havea greater or lesser number of carbon atoms, most often from five to 14,without counting the radicals of substitution which the cycle can carry.The invention can be put into operation with a-dithiols such as, forexample, those of, phenylene- C,H (SH )B2, cyclohexylene-C H, (SHcyclopentylene C H (SH)B2, naphthylene C l-I,(SH),, or the like possiblycarrying substitutions, especially of alkyls hav- 0 ing one to 18 carbonatoms.

As far as the nitriles are concerned, they correspond with the generalformula R-CH -CN, in which the radical R can be aliphatic,cycloaliphatic, arylic, possibly substituted. Thus, R can be akyl,alkenyl, aryl, alkaryl, aralkyl, arylene, cycloalkyl or the like. Mostoften this radical contains one to l6'carbon atoms; it can, for example,be methyl, ethyl, propyl, propenyl, butyl, butenyl, heptyl, heptenyl,phenyl, methyl-phenyl, diethyphenyl, chloro-phenyl, naphthyl,cyclopentyl, cyclohexyl, etc. Although the reaction can take. place inthe presence of a solvent, the use of this latter is not necessary, andexcellent results are obtained by direct heating of a nitrile with thedithiol chosen, this latter being able to be in excess in relation tothe stoichiometric proportion corresponding to the equations givenfurther on I and II Without prejudging the mechanism of the reaction,one can illustrate the preparation in accordance with the invention bythe following equations.

This illustration correspknds to the most simple case where the startingdithiol is ethane-dithiol, the reaction is analogous with otherdithiols.

When one or both carbon atoms in positions 4 and 5 of the dithiolancarry substituents, thepreparation generally leads to a mixture ofisomers. In fact is in trans.

The non-restrictive examples which follow illustrate the invention.

EXAMPLE 1 One beats for 8 hours at C a mixture composed of:

94 g, or 1 mol of ethanedithiol,

58.5 g, i.e. 0.5 mol of cyanide of benzyl,

0.2 g of triethylamine as catalyst.

The raw product obtained is distilled; the fraction passing at 140 Cunder 0.2 mm of mercury is then filtered over a column of alumina, thewashing agent being composed of ether of pertoleum, containing 10percent of ethylic ether. After evaporation of the washing agent onecollects 60 g of benzylidene-Z-dithiolan- 1.3, which crystallizes; thatrepresents a yield of 62 percent in relation to the cyanide of benzyl.This com pound melts at 44 C.

EXAMPLE 2 The product thus obtained is a mixture of two isomers ofmethyl-4-benzylidene-2-dithiolan-1.3 liquid. The weight of this mixtureis 26.2 g, or a yield of 42 percent.

EXAMPLE 3 One heats for 16 hours at C a mixture composed of:

37.6 g or 0.4 mol of ethanedithiol,

26.2 g or 0.2 mol of o-tolylacetonitrile,

0.1 g of triethylamine.

The raw product obtained is washed with 20 percent soda, in order toeliminate the excess of ethanedithiol. It is then distilled; thefraction passing at 132-133 C, under 0.15 mm of mercury, is filteredover a column of basic alumina, the washing agent is composed of etherand of ether of petroleum (l/4). After evaporation of the solvent, onecollects 22.9 g of o-xylidene-2- dithiolan-1.3, or a yield of 55 percentin relation to the o-tolylacetonitrile.

EXAMPLE 4 A mixture composed of:

37.6 g (0.4 mol) of ethanedithiol,

30.3 g 0.2 mol) of cyanide ofo-chlorobenzyl 0.1 g of triethylamine. isheated for 7 hours at 170 C. The raw product is treated with soda toeliminate the excess of ethanedithiol and it is distilled, the fractionpassing at 140 C, under 0.15 mm of mercury, is then filtered over acolumn of basic alumina; the washing agent is a mixture of 1 part ofether with 4 parts of ether of pertole- After evaporation of thesolvent, one collects 28.5 g of o-chloro-benzylidene-Z-dithiolanl .3which represents a yield of 62 percent in relation to the nitrile.

EXAMPLE 5 One heats for 8 hours at 165 C a mixture composed of:

18.8 g 0.2 mol of ethanedithiol,

15.1 g 0.1 mol of cyanide of p-chloro-benzyl,

50 mg of triethylamine.

The raw product is distilled at the end of the reaction; the fractionpassing at 146 C under 0.15 mm of mercury crystallizes. This compoundmelts at l04-105 C; one collects 14.6 g, or a yield of 67 percent inpchlorobenzylidene-2-dithiolan-l .3

EXAMPLE 6 The mode of operation is the same as in Example 3, but onestarts with 0.2 mol (26.2 g) of mtolylacetonitrile. One then obtainsm-xylidene-Z- dithiolan-1.3, with a yield of 50 percent. The productobtained is a liquid.

EXAMPLE 7 In Example 3, the ortho-tolyl-acetonitrile is replaced by 0.2mol of para-tolyl-acetonitrile. The body obtained, with a yield of 60percent, is para-xylidene-2- dithiolan-l .3, whose point of fusion is 50C.

EXAMPLE 8 The mode of operation is that of Example 4, except that thecyanide of ortho-chlorobenzyl is replaced by its para isomer. With ayield of 67 percent, one then obtainspara-chlorobenzylidene-Z-dithiolan-l .2, with a fusion point of 104 C.

EXAMPLE 9 In a laboratory autoclave one heats at 200 C, for 2 hours, amixture of:

0.1 mol (11.72 g) of cyanide of benzyl, that is to say,

phenyl-acetonitrile, 0.1 mol (15.62 g) of tolylene-dithiol-3.4,

its point of fusion is 132 C.

EXAMPLE 10 Operating as in Example 9, one replaces thephenylacetonitrile by 0.1 mol (13.1 g) of para-tolylacetonitrile. Onelikewise obtains with an almost quantitative yield,methyl-5-(p-xylidene)-2-benzodithiolan- 1.3, which melts at 140 C, afterrecrystallization in the mixture of ether of petroleum and benzene.

EXAMPLE 1 l The operations are the same as in Example 9 and 10, but thenitrile used is parachlorophenyl-acetonitrile (cyanide ofparachlorobenzyl taken in the same proportion of 0.1 mol 15.15 g).

One then obtains methyl-5-(p-chlorobenzylidene)-2- benzodithiolan-L3,which melts at 184 C after recrystallization in benzene. The formula ofthis body is similar to that of Example 9, except that the benzenicnucleus of the benzylidene left of the carbon at 2 carries one atom ofchlorine in para of the group CH=.

The structure of this compound, just as that of the products obtained inExample 9 and 10, has been confirmed by analysis and spectrography IR,UV and RMN.

We claim:

1. A process for the preparation of methylene dithiolane having a doublebond between the carbon atom in position 2 of the dithiolane ring and acarbon atom exterior to the ring, which consists essentially in heatingat a temperature in the range from to 250C. an alpha-dithiol selectedfrom the group consisting of C C, alkane dithiols, C C arylene dithiols,C:,C cycloalkane dithiols, C -C alkyl substituted C,,C arylene dithiolsand C -C alkyl substituted C,,-C cycloalkane dithiols with a nitrile offormula R-CH CN wherein R is a C -C alkyl, alkenyl, aryl, alkaryl,aralkyl, arylene, cycloalkyl group, in the presence of an amine.

2. A process according to claim 1, wherein the amine is a C,-C, tertiaryaliphatic amine.

3. A process according to claim 1, wherein the reaction temperature isto 180C. for the alkane dithiols.

4. A process according to claim 1, wherein the reaction temperature isfrom to 220C. for the arylene dithiols.

5. A process according to claim 1, wherein said alpha-dithiol is derivedfrom a member of the group consisting of a C C alkane 1,2-dithiol, C Calkane 2,3-dithiol, and a C,--C alkane 3,4-dithiol.

6. A process according to claim 1, wherein said alpha-dithiol is derivedfrom a member of the group selected from the group consisting of phenyl,halogen substituted phenyl, tolyl, and xylyl.

9. S-methyl 2-arylidene 1,3-benzodithiolane,

wherein the arylidene group is benzylidene, chlorobenzylidene, orxylidene.

2. A process according to claim 1, wherein the amine is a C2-C6 tertiaryaliphatic amine.
 3. A process according to claim 1, wherein the reactiontemperature is 130* to 180*C. for the alkane dithiols.
 4. A processaccording to claim 1, wherein the reaction temperature is from 170* to220*C. for the arylene dithiols.
 5. A process according to claim 1,wherein said alpha-dithiol is derived from a member of the groupconsisting of a C2-C12 alkane 1,2-dithiol, C2-C12 alkane 2,3-dithiol,and a C2-C12 alkane 3,4-dithiol.
 6. A process according to claim 1,wherein said alpha-dithiol is derived from a member of the groupconsisting of C2-C12 alkane substituted C5-C14 cycloalkane and C2-C14alkane substituted C5-C14 arylene dithiols.
 7. A process according toclaim 1, wherein the nitrile is an aryl-acetonitrile.
 8. A processaccording to claim 7, wherein the aryl is selected from the groupconsisting of phenyl, halogen substituted phenyl, tolyl, and xylyl. 9.5-methyl 2-arylidene 1,3-benzodithiolane, wherein the arylidene group isbenzylidene, chloro-benzylidene, or xylidene.